Hydraulic speed governor



Jan. 26, 1954 J. s. DALE 2,667,345

HYDRAULIC SPEED GOVERNOR Filed Jan. 17, 1950 6 Sheets-Sheet l I M 5P5 DRO when,

26 22 I; I 3 /a0 g a 7 27 SPEEDIWI 22 IN VEN TOR.

ATTORNEYS.

J. S. DALE HYDRAULIC SPEED GOVERNOR 6 Sheets-Sheet 2 INVENTOR.

Jan, 26, 1954 Filed Jan. 17, 1950 Jan. 26, 1954 J. s. DALE HYDRAULIC SPEED GOVERNOR 6 Sheets-Sheet 3 Filed Jan. 17, 1950 Filed Jan. 17, 1950 J. S. DALE HYDRAULIC SPEED GOVERNOR 6 Sheets-Sheet 4 ATTORNEYS.

Jan. 26, 1954 J. s. DALE 2,667,345

HYDRAULIC SPEED GOVERNOR Filed Jan. 17, 1950 6 Sheets-Sheet 5 f 2 f:9./ j I I 'm 25 28 /20 2&

Z l 9 Q IN V EN TOR.

%Aep @442,

ayflm 4 ATTORN E Y 5,

Jan. 26, 1954 J. s. DALE HYDRAULIC GOVERNOR 6 Sheets-Sheet 6 IN V EN TOR. jdep mfim e A TTORNEYS.

Filed Jan. 17, 1950 Patented Jan. 26, 1954 UNITED STATES PATENT FFICE.

HYDRAULIC SPEED GOVERNOR Joseph S. Dale, Rockford, Ill., assignor to Dale Hydraulic Controls, Inc.

poration of Illinois Rockford, 111., a cor- Application January 17, 1950, Serial No. 139,076

20 Claims.

stant speed notwithstanding large variations in load. While my invention herein disclosed, and the novel structural features embodied therein, have broader application than merely in maintaining an engine speed constant, their principal application is in that field.

All constant-speed governors, whether hydraulic, mechanical, or electrical, operate broadly on the principle of negative feedback; that is, in all such devices a variation of speed is caused to produce in the fuel-control apparatus a change tending to restore the speed to its former value. Each change of state of the controlled engine thus sets into motion a train of events which tends to overcome or cancel such change of state.

While the broad governor principle defined in the preceding paragraph has been well known for many years, its practical employment to achieve truly constant speed notwithstanding substantial load variations has led to endless difficulties and only limited success.

The greatest practical difficulty which has faced designers of constant-speed governor apparatus has been the elimination of hunting. This effect arises when the counter-action taken in response to a change of state of the engine is so great as to cause the engine speed to overshoot the desired speed. In other words, hunting will occur when, in response to an increase in load, the governor increases the engine fuel supply to such an extent that the speed increases, notwithstanding the added load, to a value beyond the desired value. turn react upon the governor and cause the fuel supply to be reduced to slow down the engine. Thereupon the fuel reduction may cause another over-shoot in the direction of slower-thandesired speed. If the engine is hunting on both sides of the desired speed, several cycles of overshoots may occur before the engine settles down to a constant speed again after its normal operation has been disturbed by a change in load.

Means have in the past been devised for compensating governors to avoid over-shoots and thus eliminate hunting. In the broad sense, these compensating devices have all permitted corrective governor actions to be initiated rapidly,

but, near the end of a given corrective action, have delayed and opposed such action. If the compensation be correctly adjusted in quantity and timing, a compensated governor should be This over-shoot will in.

able to restore engine speed to normal quite rapidly after a change in load, without either over-shoots or hunting.

Prior-art speed governors for internal-combustion engines have, however, had a substantial operating defect notwithstanding the use of com-' pensation. This defect has resulted from the fact that in internal-combustion engines engine speed is not a linear function of either fuel supply 01' load. As a result, when a governor-controlled engine is hunting, the speed over-shoots above I and below the desired speed are almost never of equal magnitude. The recovery time on acceleration will be two or three times the recovery time on deceleration, or vice versa. As a result,-

an engine governor provided with prior-art compensating means could never be adjusted to anoptimum setting in which the governor gave rapid restoration of normal speed without hunting on both acceleration or deceleration. Com-- plete elimination of hunting in prior-art devices has in general been accompanied by sluggish response in at least on recovery direction. Since rapid restoration of normal speed is usuallyimportant, practical engine governors, therefore,

have normally been compensated on a compromise basis. In other words, the compensation has usually been set to that value which seemed to give most nearly'stable operation consistent with rapid response to load changes. 7

One of the principal objects of this invention is to provide a speed governor for internal-com-* bustion engines wherein the compensation can be separately adjusted for accelerative and decelerative effects, with no mutual interaction between the adjustments. The attainment of this object represents a very important advance in the art, since it makes possible the construction of an engine governor which will maintain an engine at constant speed within very wide load limits without any over-shoots or hunting effects Whatever.

Another object of my present invention is to provide a hydraulic speed governor for a prime is provided for closing down or shutting off the engine without necessity for adjustment of or tampering with the delicately balanced pilot valve which constitutes the sensitive control member. In my structure, the pilot valve, on a shut-down operation, performs its usual regulating function, and the course of flow of the hydraulic fluid within the governor is altered so as to shut off completely the fuel supply rather than to hold the engine at constant speed.

A still further object of my invention is to pro-.

. t tele ih parti u s ifts -iii pilotvalve pgsit on to tame within istics an the controlled engine.

bimetallic element built into the governor frame structure affords automatic compensation for loss of force of the Speeder spring with increased-' temperature and thus eliminates or greatly. re-; along-the duces the falling off of speed ordinarily occurring as the speeder spring a cold start.

Still another object of my invention is to provide a means for achieving manimumpi-lotvalve sensitivity which involves placing a non-positive warms up folli iwi ng i coupling between a rapidly rotating shaft enethe body member of the pilot valve. This coupliiig causesthe pilot valve member to rotate and thus maintain at a minimum the frictional resistance offered by thepilot valve toaxia-l movement: Still-another object of videyin a hydraulic governor for internal-com; bustionengine's; a novel and simplified variable speed droop. mechanism which is dependable, finely: variable and inexpensive to construct:

yStill another-object ofmy invention is to provide a: fly-weight governor for internal-com: bustion engine'swhich can regulafte the speed of the-enginvdown toany desired low value no matter how slow. Tlhi's desirable object is achieved in my invention-by novel construction of the pilot valve 1 and speedr 1 springeffective to maintain contact and tension between the speeder-spring and pilot valve even at zero speedi Another-object oim-y invention is to provide,- in ahydraulicgovernonan automatically actuatedahydrauliq pump which is energized by the contrplledengine; anglinwhich automatic conrolfzmean a e; e id d .ier me me h Mi e .e i e ye e e engine with which the gove mum ressur n nishe ee-u deoiher bi ci. lmv i ven i n i $9 d ma, r a ie qv n lme ee d u t n h "'ecriamsm, to

.P EeFeQe Y bi eeacteristics to; be-ftail d lto suit. the charactern s e imi a th s,

jfotiiertijjfdt'sfand van'tagesof I eeds.

I have shown a typical eiznbom "e "of lily/iiivention the accompanying. are 'fngsl' Figure "Ian viewer: m'y illiis ve e'dvei'etrg t lien the casing 'ifi'pie'ee'a s for ffitr'maruse. "2' s a bottom new of the fi'g. 1 structure; Fig. sis a new inside "elevation or fine autismw being taken 've' 'spee'd" 'g'over'n'or, the vie the left as the observer faces the, govern eis a front elevation new: the illustrat g'o 'inqr, snowing 'i'ri de'taii' the control and in- 12 panel. Fig. 5'is auiagreimfiiatic'view11 lustrati'ngi the manner which eed' gov: i fi iir might be connected to a large internalcombustion engine for maintaining" the speed t ere-offer a constant value (respite variations in load, Fig. dis a top View ,ofmy governor apparatus as it appears with thetopcasing "plate removedy alternatively, it might Ice-described a's 31-. F 7 is a plan s'ectional vietvoi my spee governor taken along the linea -rot Fig; 3. Figi '3' is 'a sectional 'si cleelevation View showing myillustrative governor as it would appear from the side with one side wa'll of the-casing broken away: Alternatively, Fig. 8 fr'iight bedes'cribed as "a "sectional view 'takenfalong the linet'-{B or Fig. f'Fig. 9 is'a perspective viewbf a me chanic'allinkage "structure is employed in my-invention is to promete-a 'as nydraui" f a cylinder.

4 tee-revel shut down cofitiolfiwli'i are of the features of my invention? 'Fig 1i) is a semi-diagrammatic view of my governor which is substantially a sectional view in the vertical plane irregular line I6-HJ of Fig. 7. To 11 showing in a single figure, however, n tliegpasageways and valves, the of such components are slightly e g. was compared with the other figures which-shew their actual position in the representative embodiment of my invention. Fig? nae-a vertical sectional view of certain apparatus located in the upper portion of the casing; the section being taken alongthe line il'i"-i i in Fig. 6. Fig. 1-2 is a sectional view taken through; the central casting which carries-the bore for the pilot valve; the planeof theseotion dicated by the line IZ- -IZ ein F-ig. '7 Fig.1 sectional detailview of of- Fig. 12, showing the structural detailsof gears whichfunction-as anoil'pump an'd'a-re also part or the gear trai n which drives the-fiy-Weight" mechanism. 15; "is aysctional 'view show mg a modif ed formof'gdvfntr ifl'wiii'ch 1 peak Hydraulic ressureis..;e6nt bi1ea at "a? tion of engine speed; afidi igsfl'fiand. 7 are.- spective andsectiohalview's respeae other modification e: 'rh'ygovrhd control steamed over'th rate er draulic fluidfrom the-pi-lotlvalve tame serve.

As retirement: shown i'n Figs, 1-4; the mietrated governor is enclosed within a cast Housing 26, preferably formed of aluminum. "The casing '2 ii is provided with a top plate tweed a bottom plate 20b, respectively secured to the main casing ifiwith "screws anaeficnrero provi'dea fully enclosed, li'ciuidtight'ho'using.forthe eeverncr apparatus. I

The interior or the housing, in: addition "to. carrying the operative elemehtsof' the governor, functionsas asum-por reservoir; "at at sphere eressure; for the; light'oil for otl'ier liquid. "efnhydraulic said-w ee necessary." the gas "pressure within casingds'at? atmosf heric value, anair' vent 29h maybe provided eratio'niof the governor; should be slightlymore half way'upth'e si'deoFthepa'sing; in 'tlie part may; embodiment illustrated in the n w; ings, Ihavejshown "a ranspa ent-glass or pl'as} tiC'WiIlddW 25 the Trdilt of the casing to Frovidea convenient means ofob'servingthe oil evel;

Qonn ectidn betwentheshaftof the controlled engine and ov'e'indr may be inaeie through t w Sha f 1 u V dew-aware m the bottom (if the The oh: 'ut onod'hfiidl slia ft i2 is horizontal-1y meme andmountd' in suitable 'bearihgsin the Siaes casing 21); for don'venience m instaltron vifith'a variety of engines/shaft 22 is extended be (ind-the casing afit'hoth ends: Shaft 2-2 secured against aii'ia'l' movement, its *rot'ation be: 'g dVeYfie "15y the control abtibn of 'the gdv efnof. Infuse, thesha'fVZZ'may be' corinecte'd suitable llhkl'g 116 the fiil 'cc iritr ol 'of the: e'm

Fig. shows, diagrammatically, a typical installation of my governor for the control of an internal-combustion engine. Engine I9 is provided with an output shaft Illa, coupled by bevel gears |9b to shaft 2| of my governor which, as shown, is mounted at a convenient location adjacent the engine; Control shaft 22 is provided with a lever arm 22a keyed thereto, and arm 22a is coupled by conventional lever linkage to fuel control 23 of engine 19. As connected in Fig. 5, my governor will control fuel control 23 in response to the rotation of shaft [9a so as to maintain the speed of the engine at that constant level set by manual adjustment of my governor.

As may be best seen from Figs. 3 and 4, the upper portion of the face of casing 20- is provided with an instrument panel 30 which carries the manual controls with which my governor is adjusted and regulated. A manually operable knob 26 serves as a speed control, affording to the operator free choice of the speed at which the governor will hold the engine being controlled.

A shut-down control 21 is the manual control which actuates a novel mechanism which is one of the special features of my invention. As will be more fully described hereinafter, movement of the shut-down control. to the off position causes the governor to stop the engine promptly by cutting off the fuel supply without in any way interfering with the normal operation of the sensitive pilot valve.

Y Manual control 28, on the instrument panel immediately above the speed control, is the speed droop control member. As is familiar to those versed in the. engine-governor art, speed droop is what might be called intentional underregulation. That is, when speed droop has been introduced into a governor, it will, in response to load increases, supply additional fuel but not quite enough to compensate for the added load. Speed droop is used when a number of engines are being operated in parallel, as in electric generating stations, etc. In such stations, it is usually desired that a single engine take all variations in load, while the other engines are expected to operate under substantially constant load at all times. This effect can be achieved by introducing speed droop into the regulation of all of the engines except the one which is to take the load variations. The apparatus herein disclosed for providing speed droop is another of the distinctive features of my invention and it will be fully described hereinafter. Referring particularly now to Figs. 10, 12, and 14, it may be seen that bottom plate 20b carries on its upper surface a central casting 200, which serves to support a considerable portion of the governor apparatus and which contains cylindrical bores for the pilot valve, the servo piston, and other important parts of the apparatus.

A central bore 35 in casting 200 extends vertically through the entire casting. Casting 200 should be made of thesame metal as is employed for the casing proper; aluminum or other light metal is preferable for this purpose.

' Shaft 2| is supported in the lower end of bottom plate 20b by anti-friction bearings 36 and stufi'ing box 31. The upper end of shaft 21 is keyed to a gear member 38which is carried. in a recess 39 machined into the lower end of casting 200. The respective hub portions of gear member 38 are supported in a vertical bore in bottom plate 20b and the lower end of bore 35 in casting 20c.

Gear 38 is positioned to mesh tightly with a. second gear 40 of identicalsize. Gears '38 and ends. A ball-check valve 43 is mounted in vertical bore 4| immediately below transverse 'bore' 42, while a similar ball-check valve 43a is mounted in vertical bore 4| at below transverse bore. 42. Aball-check-valve 44, mounted in a branch bore 45, connects bore 4| to the outside of casting 200; that is, to the sump or oil reservoir. A similar ball-check valve 44a, mounted in a branch bore 45a, provides a connection to sump for vertical bore4la. Transverse bore 42 passes through the center of the main vertical bore 35 in casting 290. A steel sleeve 46, shrink-fitted into bore 35, is provided with'five annular res cesses, each of which is provided with a port connecting the annular recess to the interiorof the sleeve. On the drawings the annular recesses are denoted 4'l-5l respectively, taken in order from the top of sleeve 46 to the bottom, while the ports associated with the respective recesses are denoted 41a, 480., etc. Ports 41a, 49a,

and 5m are relatively large in size and, aswill become clear hereinafter with the description .of the pilot valve, their dimensions are not. critical. Ports 48a and 50a, as shall hereinafter be stated in detail, are control ports, and their dimensions relative to lands 54b and 540 are of critical importance. A transverse bore 52 through thewall of casting 20c connects annular recess 41 with.

sump. A similar bore 53 connects annular recess 5! with sump. The orientation of sleeve 46 with in bore 35 places both branches of transversebore 42 in communication with annular recess 49.,

As may be seen from a study of Fig. 12, rota-i tion of gears 38 and 40 in either direction willresult in the transmittal of hydraulic fluid under pressure into annular recessv 49 and .thence through port 49a. If gear 38 is rotating in one direction, oil will be drawn from sump through;

ball-check valve 44, around the periphery o fre-. cess 39 between the teeth of gears and 40,124 vertical bore Ma, and through ball-check valve 43a into transverse bore 42. Should the direction of rotation of gear 38 be reversed, oil is taken from sump through ball-check valveh44a,

carried by the gears around the periphery of. recess 39 into vertical bore 4|, and thence totransverse bore 42 through ball-check valve 43.;

Thus liquid under pressure is supplied to the in-; terior of sleeve 46 through port 49a any time gear 38 is rotated by shaft 2!, regardless of the.

direction of rotation.

The interior of sleeve 46 is machined with the; greatest care and accuracy, since it serves as the. cylinder which co-operates with the pilot valve' spool 54. This spool is provided with an upper land 54a which fits snugly the inner surface of sleeve 46 and serves to limit the upward move-.'

ment of the valve member 54. The next land on valve member 54, counting downward from its,

upper end, is land 541) which in normal operation co-operates with port 480.. The thickness of land 5422 is accurately machined to a thickness slightly less than the diameter of port 48a, the difference being of the order of a few thousandths of an inch. The next lower land on valve member 54 is land'54c which co-operates with port 50d;

sion on speeder spring 65. Thus by appropriate adjustment of speed control knob 26 the amount of centrifugal force necessary to raise pilot valve 54 a given distance against speeder spring 65 can be accurately controlled. In this manner the speed at which the governor will maintain the controlled engine may be accurately regulated.

I shall now describe the structure by which shifts in the position of the pilot valve responsive to movement of the fly-weights results in rotation of control shaft 22. i

A vertical bore 14, shown in Fig. 10, passes entirely through casting 20c, parallel to and adjacent the main central bore 35. A transverse bore connects annular recess 50 in sleeve 46 with bore 14; a similar transverse bore 16 connects annular recess 48 in sleeve 46 to bore 14.

A relatively large vertical bore 11 in casting 260 forms the cylinder which carries servo piston 18. Servo piston 18 is mounted on piston rod 19,

which extends both above and below piston 18.

The lower end of rod 19 terminates in a recess 80 in bottom plate 2%, functioning as a stop member to limit the downward movement of servo piston 18. The upper end of rod 19 passes through a bearing drilled in casting 29c and is attached by a pivot coupling 8| to link .82. An indicating pointer 83 is bolted to coupling member 8| immediately above its junction with rod 19. Pointer 83 extends forward to a point immediately behind the transparent window 24 in the front of casing 29, shown in Fig. 4 and marked load indicator. Window 24 may be provided with graduated markings. Since the position of the servo piston, and consequent position of the engine fuel control, are a function of the engine load, the position of pointer 83 provides an accurate visual indication of the degree of load on the engine being controlled.

A transversebore 84 joins the upper end of cylinder 11 with bore 14, while a similar transverse bore 85 joins the lower end of cylinder 11 to the lower end of bore 14. A packing ring 86 closes the bottom portion of cylinder 11 while allowing the lowermost end of rod 19 to pass through into recess 88, already described. A vent 80a. connects recess 88 to sump to avoid trapping in recess 80 any oil which might escape past packing ring 86. A similar vent 14a prevents liquid being trapped in the lowermost portion of bore 14.

A spool valve member 81 is carried in bore 14. As may be best seen in Fig. 9, valve member 81 has a principal valve portion 8111 which is generally cylindrical in shape but provided with two flat cutaway portions, one of which begins intermediate the ends of the cylinder and extends to the top while the other begins on the opposite side of the cylinder near the upper end and extends-to the bottom. This valve member 81a is oriented on the main spool shaft 81 in a. position such, as shown in Fig. 10, that the flat portion extending to the top of member 81a provides communication between transverse bore 84 and transverse bore 16 when the valve member 81 is in its normal, fully lowered position. In that position the other cutaway portion of member 8111 affords communication between transverse bore 15 and transverse bore 85. At the lower end of spool shaft 81 a cylindrical land 81b fits snugly within bore 14, thus normally blocking off transverse bore 85 from vent 14a.

At its upper end spool member 81 is rigidly coupled to an arm 88 extending outward at. right be locked in any desired position 16 angles to member 81. At its outer end, arm 88 is joined by a universal joint to a vertical member or link 89 extending upward. At its upper end member 89 is coupled by another universal joint to a lever 90 which is keyed to a shaft 21a. Shaft 21a is journaled in panel 30 and carries knob 21 on instrument panel 30. As may be noted from Figs. 4, 9, and 10, shifting of the manual member 21 to the off position will raise spool valve member 81. In the 01f position, spool valve 81 cuts off communication between transverse bore 16 and bore 84, providing instead communication between transverse bore 15 and bore 84. At the same time, land 81b cuts off communication between transverse bore and bore 15, instead connecting transverse bore 85 to sump vent 14a.

At its upper end connecting rod 82 is pivoted to a crank member 9| which is rigidly keyed to control shaft 22. Accordingly, shifts in the er-i tical position of servo piston 18 are reflected as rotational movements of shaft 22. Shaft 22, in turn, may be coupled by any suitable mechanical linkage to the fuel control of the engine being regulated. I I shall now describe the novel structure by which compensation is introduced in my speed governor to stabilize its operation and to avoid hunting.

A vertical bore 92 in casting 29c functions as compensation cylinder. It contains a central boreat the top which receives a vertical rod 93 extending entirely through bore 92 and seating in a recess 94 in bottom plate 2%. Recess 94 is provided with a sump vent 94m. A packing ring' 95, shrink-fitted into the lowermost portion of bore 92, serves to hold rod 93 in alignment and to permit it free axial movement without binding. At its upper end, rod 93 is pivoted to a link 96 which extends upward to a point near the top of the casing, at which it is pivotally secured to a member 91 which is, in turn, carried in a transverse slot 98 in a crank member 99, keyed to shaft 22. By a set screw 91a, member 91 can in slot 98, with in a substantial range of movement. f Rod 93 carries an upper spring seat IUI and a lower spring seat I92. These spring seats are machined to fit relatively loosely within bore 92. Floating on rod 93 is a plunger I93 which is machined toslide freely in bore 92. It is provided on. both its upper and lower faces with annular flanges which serve as spring seats. A coil spring I94 is seated on the upper face of plunger I83, i where it presses upward against spring seat IIII.

correspondingly, a second coil spring I85 is seated around rod 93 between the lower face of plunger. I 93 and spring seat I02.

A transverse bore I96 connects the uppermost part of the enlarged-diameter portion of sleeve 46 with the lower portion of bore 92; a trans! verse bore I91 connects the lowermost portion of the enlarged-diameter part-of sleeve46 to the upper portion of bore 92. A branch bore I66a connects bore I96 to a needle valve I08 communi-- eating with sump. 'Similarly, a needle valve I09 is connected by a branch bore I91a to bore I01, valve I99 exhausting also to sump.

The needle valves I68 and I99 are made manually adjustable by rod links I I6 and III respectively which extend upward toward the top'of the casing, being secured at their upper ends to a bracket II2 which extends inwardly from casing As has been previously-mentioned in tirade-,-

'seri'ption of Fig; "19', V the V needle valves 4 team ,I Heine-therein shown in ereerto "make clear their function relative to theiriassociated "streeture, "although, as may-be" seen from Fig)? or Fig. 8"; ithe'actual'position or" those valves in theiil u trated embodiment of my-invention is not on the "sectionline'HP- lfl of Fig. "I".

I" shall now describe the structure by whieh rachi'e've controllable speed droop' in 'my 'governora'pparatus. i

, "Asfmaybeiseenbest-from Figs. 6 and r1, shaft 22 -haskey'ed toi-t at mi'dp'oint--"a' crank member H3, towhichispifvotetf a link H 5; Theupper en'd-ofrlink'. I'M is pivoted to a-bifureated lever t i5 which extends forward approximately half way across the casing. 'At the precise midpoint of the casing, directly over the center or plunger fifijfthelever. me her H5 is pivoted-to asecond biforcatedflev'er member I it. hover 1H5 'two pointsof'supp'ort; atits extreme forwardehd-it is pivoted apivot rod?! litoe 'pair'oi brackets which extend backwardfrom'ithe p'anel'fefl. Tnterm'e'diate' its ends, lever" H 6" is pivoted also to a bracket (8 which isri'g'idhfbolte'd toja steel rod US. As may be best observed from Figfll'l, bifurcated lever r'nember H 5 isrcurveddownward at the "pivot point with bracket Tl f3 "50 thatthe pivots which join member "H5 to bracket H8 do not interfere with the. linkage which joins shaftna' to earn member 2 8g.

, i In'the illustrative embodiment, as s'tated'above. shaft H9 is madeof'steeL'while the casing and other" structuralfsupports Of'jthfi governor apparatus are'formed'of aluminum. I do not desire to'l'im'it myself to that particular ieom'bination of metals, but it is important in'respectzto one aspect .of my invention, as will be morev fully stated hereinafter, that shaft H9 be formed of a metal having a lower coefficient or expansion than the metal oi'whichithe casing and other structural parts are? formed;

A'pivo't' 28f, 'whic'h joins lever members H5 and [16, has an'enlarged-diameterportion which fillsthe, space between the'respective forks of lever member "H 5 "member 28 is'provi'ded' with a transverse bore, perpendicular toits axis and spaced midway "between its ends. Through the aforesaid transverse "bore,a bolt menrber .ZB'i is carried oriented with its head 28h nearest" 'the front'of'the' casing. The head '28h is pivoted'to a'linkmemb'er'2d. The opposite end of link member fisdslides in an axialapertur'e in couplingmember 280; being securedtheremby a pin f2]. A-sl'ot 122 in coupling 28c affords a limited range of sliding-movement tolinkmeinber 28d. The forward 'end' of linkmember' wc is provided Withfi? keyed-in extension 1281) pivot'edat its forward end to shaft 28a, which inturn is journaled into- "ab'ea'ring in panel" 30'.

The rear portion or bolt-23% is threaded; and it carries, threaded thereto, a cam member 28g which is shaped generally like the letter L. The shorter leg ofmember "2 8g is the-portion threaded into b'oltflli; "the other leg extends forward under pivot member 213f,- the dimensionsof cam 28g being chosenso' that its'horizontal surface "engagesthe 'lower surfaceof member 2$f-when bolt 282' is in a horizontal-"position.

f2 manual-"manipulation of knob zfi wi i resul'tfin forwardfor' backward movement-of earn se men consequent 'shift in: the line of 'c'onta-ct between earn 2 89 and plungef'iiQ which, forced upward by spring 65, presses against"cam -28 g"orr its under 7 side. As cam 28g moves across-the clung-c1 53 the The under "side of earn 289 provided with a-rcuate downward-extension i 23 which is carefully-'rnachined to former sect-erof a circular eymeer. "The open end of bolt28i isprovided with a-' -keyed-'on stop firlern mer '28 which limits the outward movement of cam member 25 'As maybe seen' from'FigJlLrotation of 'shaft zta by relativeposition or arcuate-extension an pivot 28] is altered.

'OPEEATION It will be assumed 'for purposes" of this di'seussion of operation that my"iiiverrtionf-hae'been snitably mounted adjacent-an engine that shaft 2 i has been 'mechanicalIyroiipled engine drive-shaft, that control mean has ween coupled. to the engine fuel 'controlyand that the governor casing has beenfilledwi-tho or other suitable hydraulic fluid approximately at to'the levehoi the :top of central casting 29C,*alr passageWays, cylinders, "arrd other open spaces therebelow"seine, filledalso. I v

Initially theshxitbown control ziwill be placed in the on'gposition "andithe engine started. 'Thereupon the shaft '2 i will Ebe--*Set "intorota tion and "the ffiy=weight' structuremourrted-'on-gear*-58 will rotate in exact syi-I'c'hrornsm withshaft' (Meanwhile thefpilot valve member-$14 e commence to rotate; due-t0 torque su pree by spring 51".) Y 7 I As [the fi -wei'ghts 6 move odtward; pilot valve member as is "raised 'iznti'l" *ittoccuriiesf its normal operating'iposition wherein lands 'Hb-an 4e are centered "with respect to "ports flfia and "respectively; When that c "dition istreaclred,the

' enginewill stabilizeitsspeed'. Anysubsetiuent weights 6 iito shiftieither or outward. Should the ienginespeed' npfas "a 'resiilt' era light en'ed load, fly-Wei *64 tiilh'nove ms; ingh pilot valvefiito rise. 'Ihiswili'resifltin' increased fiowofhydrairlic i'fiuidout ferpo'rr' ie into transversmbore'fi "(Itshould beborne inmin thatas' soon as rotation ofishaft *2! emmeme the gear pump formed? by gears "38" were creates and maintainsfa substantifal 'fiuid pressure the chamber iwithirr sleeve "55 b'etweendarfd's Mlra'rld 54c.) With'increased *fiowilof hydraulic firiid' of portfwa into bore :75;thelinereasedifinidjpresr sure is transmitted"throughboresxW andte" L ito 'theupper [end of chamberi'l'. A's oiliiows' into chamberi'l', servo'bistofi'i is 'forc'e'iidownwarol, the oil.below.the piston being free to escape"to s impithroughbores Hi, a-1375 arfdtp'ortmeta and" em; Lowering of servo permeacause'srot'ati'onoi shaftf22 and consequent. reduction of the quantity of 'fuel supplied to therengine. "This of course "slows down the engine and restores the speed to normal. 7 a 7 'If, as a result of heavier load,"theen'giner'spee'd tends to fde'crease', fan. exactly" 'sirnilar'seiiesfoi efients, irlitiated'fwhenpilot valve "member '55 drops,?leadsito mard"movement of servopisten i8 and. consequent increase in""the' "erfgine fuel upply. r .v "stabilizationof the'controlling action is aceomplished by means-of {the 'ccmpensatmg apparatus heretofore described indetail. "Its-"cperationfis bri'eflyas follows: fivh'en; in response to an added load, fpliot valvefi' l' "drops, the lowering of land 54d" at once" creates a super atmospheric pressure in bore i6! andvthefupper'endof chamber 2 This reduces the"tension .:onspring ramma s tendency. of the added pressure'is'to' drive'irhin'ger Hi3 :downward and 'eompress Lsprihg "E85. illiquid under"plunger"'i@3"isfree'to escape, since" iowerneedle valve I08 at a controlled rate.

' ment of needle valve I08 will thus permit stable ing of land 54d results in partial uncovering of port 55 which leads to sump." When, in response to the lowering of the pilot valve 54, the servo piston 18 rises, it causes link '96 to rise also, thereby increasing the compression on spring Hi5 and thus further decreasing the compression on spring I84. This increases the fluid pressure within bore I01 and the chamber below land 54d. Meanwhile, however, hydraulic fluid has been at liberty to leak off slowly through needl valve I69, so that the hydraulic pressure below land 54d which tends to oppose the downward movement of valve member 54 diminishes gradually with time as liquid escapes through valve I69. The magnitude of movement of link 96 resulting from rotation of shaft 22 may be controlled within wide limits by adjusting the member 9'! Wlthll'lSlOt 38, since the effective length of the crank member 99 may be thereby varied.

By careful adjustment of the position ofmember 91 in slot98 and the bleed rate of valve 109, the magnitude and duration of the counter-forces set up by the compensating mechanism can be made to eliminate hunting entirely and achieve a clean, rapid return to normal speed following deceleration resulting from added load. The object of the adjustment should be to avoid overshoot and obtain precisely that degree of damping which accomplishes stabilization without overshoot. rapid return to normal speed following the imposition of added load on the engine.

Should the engine rise in speed as a result of lightened load, pilot valve 54 will rise, port 55 will be opened to bore I01, the hydraulic pressure in bore I06 will become higher than normal, and plunger I03 will be forced upward, thus compressing spring I04. The shift in the position of shaft 22 following the lowering of servo piston I8 will cause link 96 to be lowered, thus increasing still further the compression of spring I04 and the hydraulic pressure in bore I06.- As before, this super-normal pressure is transient, since liquid is free to flow out to sump through Adjustoperation of the governor to restore the engine to normal speed with maximum rapidity following acceleration due to lightened load.

It is important to observe that the adjustments of valves I 08 and I09 are entirely independent of one another, since any time one of the valves is functioning the other valve is effectively bypassed to sump by port 55, the appropriate side of which is uncovered by any movement of pilot valve 54. Thus, with the structure Iihave described, entirely independent compensation adjustment on both acceleration and deceleration is possible. Instead of seeking an adjustment which is at best a poor compromise between the two conditions, as prior-art structures required;

my invention permits accurate and independent adjustment of compensation for both acceleration and deceleration.

The magnitude of centrifugal force necessary to cause fly-weights 64 to attain normal operating position depends, of course, on the tension ofspring 65. (The tension of spring5l, being constant, need not be considered in this connection.) Adjustment-of the tension of. spring 65 may be accomplished by any shift in the vertical orientation of spring seat 68. Various factors can accomplish movement of spring seat 68; circumstances under which these factors operate will not be described in detail.

'Inat adjustment will provide the most moved to an off-center First, spring seat :Gllmay bearaisedor lowered by manual adjustment of knob 261cm the instrument panel. This causes pinion .10 and rack I2 to shift their relative positions, with the result that sleeve 61 moves up 'or down, thus raising or lowering spring seat 68. This adjustment is employed when the operator desires manually to change the speed of the controlled engine.

As the governor warms up? after a cold start, the temperature of all the components,. including speeder spring 65, increases. It is a wellknown property of springs that the force exerted is a function of temperature and, if the temperatureof a spring is raised, greater compression is required to achieve a given force. Since, in the present invention, the casing, central casting, and other structural parts are made of. a metal having approximately double the thermal coefficient of expansion as the material of which post H9 is formed, heating of the governor after a cold start results in raising the frame members substantially more than the pivot by which bracket I I8 is anchored to lever I I6. This results in gradually increased pressure on plunger .69

'. by cam 28g as the operating temperature rises.

I have found that by using metals having a ratio of thermal coefi'icients of approximately two to one, such as aluminumand steel, almost perfect compensation for thermal changes can ,be achieved in this manner. In other words,,with the present invention, there is substantially no change in controlled engine speed between a cold start and the stable temperature at which the governor settles down after continued operation. This represents a great improvement over the operation of conventional governors, since they usually require almost continual readjustment for a long period after a cold start,

Normally, whenno speed droop is desired, knob 28 is set at the position whereat arcuate portion I23 0f cam 289 is in contact with the physical center of the upper surface of plunger 69. Since surface I23 is a sector of a circular cylinder, and sinceits center of rotation is pivot member 28 centered directly above the. midpoint of plunger 69, crankII3 can shift its-position in response to movements of shaft 22 without affecting to any extent the position of plunger 69. If, however, manual knob 28 is rotated in either direction from the neutral point, cam 28g will be position relative to pivot 28f, and thereafter any rotation of shaft 22 will cause a shift in the position of plunger 69 with resulting variation in V the tension of speeder spring 65. Thus, by appropriate adjustmentof knob 28, my governor can be made either to maintain constant speed under wide variations in load, drop slightly in speed in response to added load, or increase slightly in speed in re sponse to added load. In other words, my inven- .tionmay be caused to over-compensate or undercompensate for load changes, should such result be for any reason desired. (As heretofore stated, the usual reason for employing speed droop is to permit control of load distribution between a number of engines being operated in parallel.) While speed droop is not of itself new, the novel physical structure with which it is accomplished in the illustrated embodiment gives avery precise and accurate control over the degree .of speed droop without in any way interfering with the normal functions of the governor and is accordingly considered by me to be an important and novel aspect ofimy invention. :f

In prior-art structures, shut down of the l "the lower end of a valve sump when poppet camera zfengineihasmormally beenuaccomplished by so'me device which: forodl the'pilotfvalve: the dirac- :move resp'onsive'ly 'to deceleration. such ari rangem'ents are-unsatisfactory in that they interferewith the' delicate balance of the most'cr-itical 'element 'inthe entire governorime pilot v'alve member. -'I consider that forcing-what member a given "p osition' by impositionofqa forc'e overfidiflg? t e influence df the -fiWweights is exceed- 'gly *baid praetice and one which :is-likely- 'to result in lower'ed sensitivity 'and accura'cy- 'of control.

my present invention, f hjave provided a novel and-mueh'moreelegant shut down means. "In my invention; ='whe'n the manual shu-t d own =cr'1't1o1 "2 is' shi'fted to the-off position, I spool member 81 israis'ed, "with the result-that transverse' bore 15,*normal1ycommunicating with bore j 85,*1's"plac'ed in communication with bore 8 3, "while 'bor'e '85, is vented" to-snmp. As a result, I slightest downward "movement of the pilot f valv e'im'mediately produces downward movement thefservo-pistonfis which in turn causesi =further downward movement-off the "pilot valve' '5 5.

process continues untiltheengin'e fuel supply is' entirely shut off and the engine stopped. Thus. by my'invention;thepilot valve is caused to turn off-the engine without beingforced mm itsnormal' operation in any' way fun the contrary, it doesexactlywhat it'n'orm'ally does in'response toideceleration;butthe effect iof' that action is to'stonthe engine.

TherFigme 1 modification Figflfi shovvsa modified-"term of my governor inwhich provision has-been made'for controlline, asa'iunction of the "speed cit-"the controlled -;engme, the maximum '-"hydranlic i pressure deiveioped "by thegearpump'tfiflfl. Whenthe' controlled engineis' bei g operated" at a very high speed, the. f hydraulic "pressure develobed' bygear pump 38, "40 can 'reachr an excessive value, with "the result that hydraulic fluid is driven into the 'servo-cylinden'iand the servo is caused to function more rapidly than the:engine can respond changes, in the rate of fuel'feed. 'flhisstate of affairs lean, on occasion, cause "jerky; unstable operation of the controlle'd en'gine. V I

' The -moiliflcation Lof Fig. 15 discloses means whereby the pressure "f the" hydraulidfluidifed into annular recess 49 [by l'gear pom-p" 38,;40 can beheld et a reasonable value "evenwhen' the controlled engine is operating "atf'a very "high speed. g

-Asmay be seen from 'theportion' of Figlljfi .tilfichislbroken away to show internal structure, Lhaveprovided a relief valve. apparatusfwhich eom'xmmicates with-passageway 42 by Way "of passageway 15!. and "I 5 id. Passage" I 5 la; is drilled in a plug [55 which is screwe'd'into the upper end of bore 4 I, inlieu'of plug' lza of the 'em bo'dimentshown in Figs. 1-14. Conduit T51 intersects a verticalptmssage [52,.d'r'illed in'a'v'alve housing [5-3 which is mechanically supported .byplugltli. The lower end otpassage 152 is Ionentosumrp, although it is normally closed off by .a...;ooppet valve .IEA mounted at the extreme 4 rod 156 carriedin. passage 1'52 and machined to slide snugly therein. The lowermost .end, of rod, 156., immediately above .pfonpet valve. mernber I54, is machined toiform a taperedbleed valve 156;! wilrpermit flowing of hydraulic 'fiuidfrom passa ewsz. to

' memberlfl'is open; obvi- :';ous1y,:. thezrateof iiowzpermitted =wil1ibeidepend- "arm has a vertical body "to the body and portion in opposite directions. The-uppercatrated embodiment, has a Whatthis optimum pressure is I ent ion the position of mod [561,1 the-rate fof iii-ow increasing: as rod 2 I SEC-is lowered.

' About midway vof:its.length,-rod 156 is provided withian annularzshoul'der l-5'l'--whi;ch;f0rrns the Supperseat fora coil-spring |58, the lower --spring..seat i59 .ior 'spring 1 58 being formedzcn the upperendofimember (53. Spring I5Bholds poppet 154 normally seated'over the l'ower-send of -passagel52.

Bracket 65 has, in this embodiment-ibeengpro- 'vided Witha slottba cut part-waydownirom its upper end to accommodateaanarmal60. That "each end, each 'extension being at right; angles :exte'ndingaway vfrom the body tension, denoted fl 6011., 'isiifirmlv secured: to. sleeve 6?; thus arm I60 is freeitofrise and'iaall with sleeve lfi 1 since slot 66:; il afiffor'ds' vertical .freedom to arm extension 160m "The" lower extensionro'f arm -'I 60, denoted 1 60b, is drilled and threaded to receive a' screw 1'6 l-; screw :ITG I, Sin theilluslarge iiat' he an :at' its lower end,' and its upper end. is slotted I to 'permit adjustment floy a'screw 'driver. A lock n-nt tfl provides a means or lockingscrew 16! many desired position. I

In the operation 'of'this' form ofimy invention, the screw-l'fil'can be manuallyla'djusted so' 'that the head of screw tdl comes incontact with the upper end of valverdd -l tfifiatrlthe positioniof sleeve 6'! which-corresponds to epnmum hydraulic pressure from gear nump SBJ-M; iThat-isjthe speed of the controlled engine is governedihy tne 'pcsitionof 'sle'eve fi'i fthehydraulie pressure generated {by the gear pump fi}; 4'8 is di'rectly re'snonsite to engine'speed. Screw i61 isadjustad tmengage valve rod i 56 *-at' 'that setting -o'f sleeve?! which 'gives an engine spe'edsubh "that ont-imurn hydranlic'pre'ssure isgen'erated bi 'tinstallation to "installationg'sinw I on 'the-rapidity'with vvhieh the engine s'peed responds to changes iii-"fuel supply. If the engine is very rapid in response r'elati vely large '11:)- dra'ul'icpressure-can be"develope'd to advantage bythe'gear pump38; '4 0. 11f; onthe other-hand, the engine is sluggish "in its response tochanges Jintfuel supply; then relatively "lower-ipressure is desirable. for :operation of theiservo meet-men of..the. governor.

One theproper setting for screw flti'fhas .Zbeen determinedr'it locked in, placelwith flock} pressed'downward .s'ufficientlyto raise. the speed of the controlled -engine.above that value {at which the hydraul-icpressure is atopt'imumvalue. the head-of screw tfi leengages valve rod Sigurd The modification of Figures'1c l7 Figures 16" and 17 show another modffiedi'fo jm .of my invention which'niakes'possibie fine ontrol of the "rate or flow of" hydraulic fluid horn -thepilot valve to the servo mechanism.

.The result'ofi slowing down the rate c'rndwtr fluid nto ;the..r-servo, cylinder "isjto reduce the rapidity with which. the 'iuers moiy"toftneneme is altered in respons'eto a"change'inload.""Con- :with an-extension at I a sessew trol over that reaction: time is desirable to in.- sure smooth, jerk-free, and stable operation of the. controlled. engine; In other. words, the. objectives achieved bythe modificationabout to be described arequite similar to .those accomplished by the Fig. modification, although the modes of operation of the two structures are d'iiferent, and they are not exact equivalents- The Fig. 15 modification merely maintains control over the hydraulic pressure developed by the gear pump in the governor to insure that it does. not exceed areasonable value at times when thegear pump is being driven by the controlled engine at high speeds- The structure about tobe described, on the other hand, is not limited in its efiects to high-speed engine operation, but, on the contrary, permits tailoring of the governor response-time to fit the behavior pattern of the particular engine to which the governor is connected, whether it be operated at low speed or high speed.

Thestructureabout to be described is an added feature incorporated with the shut-down mechanism (already described) which utilizes spool valve member (i1. It will be recalled that, when the engine is running, valvemember 8 in the embodiment of Figs. 1-14 normally occupies a lowered position .efiective to open fully port 85 to communication with port 75 and to open fully port-.8 to communication with port 16.

As may be seen in Figs. L6 and 17, I have provided as an additional feature, to be used if desired, an adjustment means whereby the spool member 81, when in its on position, may be caused to close off any desired part of the ports Eli and 85, thus giving a fine manual control over the rate at which hydraulic fluid can flow into and out of the respective chambers of servo cylinder H. As-may be noted from Fig- 16, .1 have provided, on arm .88, ;.a small projection ids-ere tend-ing outwardly therefrom at rig-ht angles. Projection. i 6.5 restson the upper surfacetof a cam Hi5, mounted adjacent projection 165 and carriedon a vertical-grad l-B?! the top end of which is supper-ted in a suitable hearing I GBattached to conveniently located frame bracketiii-he upper end .of rodl;6.1 is slotted (foriscrew driver adjustment)- and threaded to receive a look-nut tee. .Asgma'y be best seen j mFi-g'. .;1=7,,.the;sur-- face of cam !66 is cut to rise gradually froma minim-um level to asubstantially-h-ig-her level, and the port-ion of vcam 1,6,6- :en aged- {by pin i565 depends .on the positionwhieh ,rod- .161. is occupy- -W;henpin l-65-isresting;o n theglowestpon tion of cam I66, spool valve member 81 is in the:

same position that it occuples,;whfin in the on position, the embodiment. of Figs. 1 .16;. If,-

hOWBVBI', cam I 66 he turned, ;by rotation of rod: $51,. pin !65 gradually climbs up the: curved. edge of cam I6,6;and the on"",po sition;of;spool member 82115 raised. so thatlands' 81a gil'lhgraduallv' ver, and hu reduce the effectiv apert res :of, ports S l and 585. .Byappropriate ,adjustrnentpf rod $62, the effective .siaezof ports adendddcan be set :to any desired .value; Theoperaticn of spool member tkfimasaishut-down mechanism :is entirely unaffected zby:the::su'pplemental.apparatus .just. described, since movement manual. control member 2:1, tothe-fiofi position maises arm 88- and spool member =81 as before. without any interference iromcam 6301' .its associated; parts.

While I have in this specification describedifor illustrative purposes .a single embodiment -.of.my invention; it will she understood thaiimanyt-variations thereon and departures inmaiters. of detail. a e m b o e k led n the a t 19111 departing from the spirit. of. my invention. is. accordingly my desire that the scope of. ,my. invention be. not-limited to. the,- precise embodiment. shown. but. that such scope be determined by reference to th appended claims...

Iv claim:

1. Ina hydraulic governor Whereinmovement. of a pilot valve regulates. the. speedecontrol, mechanism of an engine, anti'ehunt mechanism comprising means operative on movementg the pilot valve to set up. a transient hydraulic pressure. opposing such movement, said means. corn. prising an adjustable valve operable to. control the duration andv instantaneous magnitude. of.

such opposing force when. the pilot valve has moved in one direction, a second. adjustable valve similarly operable when the movement of the. pilot valve has been in the opposite direction, and means. for rendering inoperative each of the valves during. periods when the other is. functioning.

2. In a hydraulic governor wherein movement of a. pilot valve regulates the speed-control mechanism of an engine, anti-hunt means operative responsively to movement of the pilot valve to create a transient hydraulic pressure opposing such movement, a pair of independently adjustable valve means. operative respectively to control the instantaneous magnitude and duration of h ppos n p u on cc erat on an fli celeration, and means eilective to render inoperative one of said adjustable means following acceleration of the controlled engine and the other of such adjustable means during dece le ra tion of the controlledengine.

3. 'In a speed-control governor for engines, said governor being of the type wherein the movement of a pilot valve regulates the speedcontrol mechanism of the engine and said pilot valve is connected in a hydraulic circuit having a pressure source and a sump, the improvement comprising anti-hunt means operative responsively to movement of the pilot valve to setup a transient hydraulic pressure opposing such movement, a manually adjustable needle valve discharging to sump and operative to control the duration and instantaneous magnitude of suchforce following acceleration of the engine, and a second manually adjustable needle valve. discharging to sump and operative to control instantaneous magnitude and duration of such opposing force following deceleration: of the engine.

4. Apparatus according to claim '3 wherein means including a land carried by :the pilot valve and cooperating with a sump port operates to by-pass to sump the first need-1e valve following deceleration of the engine and the: second needle valve following acceleration of :theengine;

5. In a hydraulic speed-control governorlor engines of the class described, a servo piston adapted for connection to the speedecontrol mechanism of an. engine, .andza'hydraulic circuit comprising a, pressure source and a sump con,- necting the pilot valve .and theservopiston', :antihunt apparatus comprising a .closed chamber containing a-port which ,disch-argesrto sump-,n

piston in the .cha-mbencoupledto .thepilot' val-ye and operative to move axially in. steptherewith, a, land on said piston member operative to divide said closed. chamber-into upnerandglower portions and normally OpBraliiVefliO. C1QS:2:Ofi :-S&i'd sump port, a pair of compensating pressure chambersmeans coupled to-gth servo pistonvc'p- 19 erative to produce in one of said chambers a super-atmospheric hydraulic pressure, a pair of conduit means respectively connecting one of said pressure chambers to the upper portion of said closed chamber and the other of said pressure chambers to the lower portion of said closed chamber, and an adjustable needle valve for each of said conduit means, said valves exhausting to sump and being operative respectively to control the duration and instantaneous magnitudeof the hydraulic pressure within said conduit means. V

6. An engine governor having a drive shaft, fiy-weights turned by rotation of the drive shaft, a pilot valve actuated by the fly-weights, and a speeder spring opposing the action of the flyweights on the pilot valve, said drive shaft, flyweights, pilot valve, and speeder spring being mounted coaxially, and a slip coupling connecting the drive shaft to the pilot valve operative to: transmit a relatively small torque to the pilot valve during rotation of the drive shaft.

'7. An engine governor comprisinga drive shaft, fly-weights turned by rotation of the drive shaft, a pilot valve actuated by the fly-weights, and a speeder spring opposing the action ,of the flyweights on the pilot valve, said drive shaft, flyweights, pilot valve, and speeder spring being mounted coaxially, and a spring member coupling the drive shaft to the pilot valve operative to transmit torque to the pilot valve from the drive shaft and operative also to impose axial force on the pilot valve in opposition to the speeder spring.

8. An engine governor comprising a casing and structural parts therewithin formed of one metal, fly-weights, a speeder spring mounted to oppose the force exerted by the fiy-weight during rotation, a movable spring seat for the speeder spring adapted when moved tovary the tension of the speeder spring, said fly-Weights and speeder spring being connected to and supported by said casing and structural parts, anelongated support member mounted on the casin and formed of a second metal having substantially lower thermal expansion coefficient than said first-mentioned metal, and means supported by said support member operative to press on said movable spring seat operative as the temperature of the casing increases to increase thetension of the speeder spring.

9. Apparatus according to claim 8 wherein the casing and structural parts are formed of aluminum and the elongated support member is formed of steel. 7

10. Apparatus according to claim 8 wherein the support member is formed of metal having a thermal expansion coefficient substantially onehalf that of the metal of which the casing and structural parts are'formed.

11. In a governor for engines, comprising a control element, fiy-weights adapted to move the control element responsively to rotation, aspeeder spring imposing force on the control element in opposition to the forces exerted by the flyweights, and a speed control member adapted for connection to an engine speed-control mechanism, speed droop apparatus comprising a movable spring seat for the speeder spring operative upon movement to vary the tension thereof, a cam mounted for rotation adjacent said spring seat and having an arcuate cam surface pressing on said spring seat, said arcuate surface being circular in section, adjustment means for sliding said cam across the surface of said spring seat to, move the center of curvature of said cam face into coincidence with the axis of rotation of said cam and selectively to either side, a manually operable control mounted externally of said governor, mechanical linkage flexibly coupling said external control to said adjustment means operable responsively to external manual operation of said control means to actuate said adjustment means continuously through its range of movement, and means coupled to the speed-control member operative to rotate the cam about its axis of rotation responsively to movement of the speed-control member.

12. In a governor for engines, comprising a control element, fly-weights adapted to move the control element responsively to rotation, a speeder spring imposing force on the control element in opposition to the forces exerted by the fly weights, and a speed-control member adapted for connection to an engine-control mechanism, speed-droop apparatus comprising a movable spring seat for the speeder spring operative upon movement to vary the tension thereof, a cam mounted forrotation adjacent said spring seat and having an arcuate cam surface pressing on the same, said arcuate surface being circular in section, said cam being supported at at least one point by a support member formed of material having a thermal expansion coefficient substantially less than that of the remainder of the governor structure, means for sliding said cam across the surface of said spring seat to move the center of curvature of said cam face into and out of coincidence with the axis of rotation of said cam, and means coupled to the speed-control member operative to rotate the cam responsively to movement of the speed-control member.

13. In an engine governor having a drive shaft coupled to a governed engine and being rotatably driven thereby, a hydraulic circuit and a pressure source energized by rotation of the drive shaft, and means for changing the speed-control setting of the governor, an adjustable relief valve in the hydraulic circuit operable to limit the maximum pressure in said circuit when the controlled engine exceeds a predetermined speed, and linkage arranged with said valve and said means to automatically actuate said valve when the speed setting of said means exceeds a predetermined value.

14. The structure of claim 3 wherein said linkage is mechanical and progressively opens said valve as th speed-control setting of said means exceeds progressively a predetermined value.

15. An engine governor having a drive shaft, fly-weights turned by rotation of the drive shaft, a pilot valve actuated by the fly weights, a speeder spring opposing the action of the fly-weights on the pilot valve, a servo piston, a hydraulic pressure source energized by rotation of the drive shaft, a hydraulic circuit comprising th pressure source and a sump connecting the pilot valve and the servo piston, an adjustable relief valve connected to the hydraulic circuit at substantially the point of maximum pressure, and mechanical linkage inter-relating the relief valve andthe speeder spring operative to open slightly the relief valve when the compression of the speeder spring exceeds a predetermined value and to open the relief valve further upon the imposition of additional compression to the speeder spring. v I

16. A hydraulic governor for engines, comprising a driveshaft, fiy-weights turned by rotation of the drive shaft, a pilot valve actuated by the fly-weights, a servo cylinder, a servo piston mounted in and reciprocable within said cylinder, a source of hydraulic pressure, a hydraulic circuit comprising th pressure source, the pilot valve, the opposite ends of the servo cylinder, and a sump, and a movable valve member having two extreme positions, operative in the first extreme position to supply hydraulic fluid to one end of the servo cylinder responsively to movement of the pilot valve induced by deceleration of the engine and operative in the other extreme position to supply hydraulic fluid under pressure to the other end of the servo cylinder under like conditions, said valve member being operative also to provide a path to sump for the low-pressure end of the cylinder in either extreme position, and manually adjustable means operative when the valve is in the first extreme position to vary the position of the valve member within narrow limits and thereby to regulate the effective rate of flow or hydraulic liquid into and out of the re spective ends of the servo cylinder.

17. In a hydraulic governor of the type having a speeder spring, a sump and a pilot valve slidably mounted in a sleeve and being movable in said sleeve in response to loadings of a speeder spring to regulate the speed of a prime mover, anti-hunt apparatus operable in response to movement of said pilot valve, comprising a land fixedly carried by said pilot valve and being slidably movable in a chamber provided by said sleeve, said sleeve providing also a port communicating with said chamber at substantially the midpoint thereof and with the sump of the governor and having a diameter slightly smaller than the width of said land whereby when said land is aligned with said port it blocks the flow of fluid therethrough, a pair of passages communicating respectively with said chamber adjacent each end thereof, said passages being separated from said port when said land is aligned with the port, and means communicating with said passages for applying transient pressures to said passages selectively and in opposition to the direction of movement of said land and pilot valve, whereby when said pilot valve is moved in one direction in response to a change in the loading of the speeder spring, said land is moved from alignment with said port, opening communication between one of said passages and said port, while a transient pressure in the other of said passages acts against said compensating land and opposes the movement of said pilot valve.

18. In a hydraulic governor for engines, a sleeve, a pilot valve axially movable in said sleeve, a speeder spring for moving said pilot valve in response to changes in loading of the spring, control means for changing the speed setting of the controlled engine, means for actuating said control means in response to axial movements of said pilot valve, a sump, and anti-hunt means comprising a doub1e-acting valve equipped with a valve shaft coupled to said control means and movable in response to movement thereof, said sleeve providing a chamber and a passage communicating with each end of the chamber, said passages communicating at their other ends with the opposite sides of said valve, said sleeve having a port therein communicating with said chamber at substantially the midpoint thereof, said port being connected to the sump of the governor, a land carried by said pilot valve and movable in said chamber, and means in each of said passages for slowly reducing a pressure increase therein to the sump pressure, said double-acting valve and passages being interrelated with said pilot valve and control means to provide a pressure on one side of said land resisting the movement of said pilot valve while at the same time the chamber portion on the other side of said pilot valve is connected to the governor sump through said port.

19. In a hydraulic governor for a prime mover, a casing providing a sump, pump means in said casing for supplying fluid under pressure to said governor, a sleeve mounted in said casing and providing a pressure port, sump ports and control ports all spaced apart, a servo-motor operable in either direction by the pressure of a fluid exerted thereon, said governor providing passages connecting each of said control ports respectively to one side of the servo-motor, spaced-apart lands carried by said pilot valve and having a width slightly less than the diameter of said control ports, means connecting said servo-motor with the speed-control adjustment of the engine, and a speeder spring and fly weights for positioning said pilot valve with the lands thereof in alignment with said control ports when the speed of the controlled engine is at the speed setting of the governor, said speeder spring and fly weights being responsive to speed changes of the controlled engine to move the pilot valve so that the lands carried thereby are moved out of alignment with said control ports.

20. In a governor for a prime mover having a casing and structural parts therein formed of material having substantially the same coeflicient of thermal expansion, a speeder spring adapted to be adjustably tensioned to establish the speedcontrol setting of the governor, a movable spring seat for the speeder spring adapted when moved to vary the tension of the speeder spring, said speeder spring and spring seat being supported by said casing and structural parts, a support member mounted on said casing and being formed of a material having a substantially lower coefiicient of thermal expansion than the material from which said casing and structural parts are formed, and means supported by said support member operative to press on said movable spring seat operative as the temperature of the casing increases to increase the tension of the speeder spring.

JOSEPH S. DALE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,204,564 Grun Nov. 14, 1916 1,337,865 Wells Apr. 20, 9 0 1,600,542 Gagg Sept. 21, 1926 1,846,716 Goehler et al. Feb. 23, 1932 2,204,640 Woodward June 18, 1940 2,268,230 Warner Dec. 30, 1941 2,324,515 Kalin July 20, 1943 2,333,184 Kalin Nov, 2, 1943 2,364,116 Whitehead Dec. 5, 1944 2,364,817 Reggio Dec. 12, 1944 2,364,853 Kalin Dec. 12, 1944 2,456,438 Kalin Apr. 5, 1949 2,478, 83 Drake Aug. 9, 1949 2,478,752 Drake Aug. 9, 1949 FOREIGN PATENTS Number Country Date 83,091 Austria Mar. 10, 1921 

